- #1
Deadstar
- 104
- 0
Right so there's this part in my notes where we begin to derive the schwarzchild solution. There's a substitution part I don't understand fully (I think) but I'll start from the beginning...The Schwarzschild Solution.
The solution corresponds to the metric corresponding to a static, spherically symmetric gravitational field in the empty spacetime surrounding a central mass (like the Sun).
Choosing coordinates (t, r, θ, ϕ), it can be shown that a metric of this type is of the
form:
[tex]ds^2 = -e^{A(r)}dt^2 + e^{B(r)}dr^2 + r^2(d\theta^2 + sin^2(\theta)d\phi^2)[/tex] (6.8)
where A(r) and B(r) describe deviation of the metric from Minkowski spacetime. Note
that for constant t and r the metric reduces to the standard metric for the surface of a
sphere. As one is dealing with vacuum, one is poised to solve
[tex]R_{ab} = 0[/tex] (6.9)
Where (I'm pretty sure) [tex]R_{ab}[/tex] is the Ricci tensor.
Substituting (6.8) in (6.9) we have, after some algebra...
--------
Then there's expressions for [tex]R_{tt}[/tex], [tex]R_{rr}[/tex] etc...
But I don't know exactly how to sub 6.8 into 6.9!
Would I be right in thinking we just calculate... (When ab = tt)
[tex]R_{tt} = R^c_{tct} = 0[/tex] where [tex]R^c_{tct}[/tex] is the Riemann curvature tensor.
Then we can use that,
[tex]\Gamma^c_{ab} = \frac{1}{2}g^{cd}(\partial_a g_{bd} + \partial_b g_{ad} - \partial_d g_{ab})[/tex]
to calculate [tex]R^c_{tct}[/tex] where we have...
[tex]g_{tt} = -e^{A(r)}[/tex]
[tex]g_{rr} = e^{B(r)}[/tex]
and so on...
Is this the right method? Seems like it's going to take a loooong while to do this though.
The solution corresponds to the metric corresponding to a static, spherically symmetric gravitational field in the empty spacetime surrounding a central mass (like the Sun).
Choosing coordinates (t, r, θ, ϕ), it can be shown that a metric of this type is of the
form:
[tex]ds^2 = -e^{A(r)}dt^2 + e^{B(r)}dr^2 + r^2(d\theta^2 + sin^2(\theta)d\phi^2)[/tex] (6.8)
where A(r) and B(r) describe deviation of the metric from Minkowski spacetime. Note
that for constant t and r the metric reduces to the standard metric for the surface of a
sphere. As one is dealing with vacuum, one is poised to solve
[tex]R_{ab} = 0[/tex] (6.9)
Where (I'm pretty sure) [tex]R_{ab}[/tex] is the Ricci tensor.
Substituting (6.8) in (6.9) we have, after some algebra...
--------
Then there's expressions for [tex]R_{tt}[/tex], [tex]R_{rr}[/tex] etc...
But I don't know exactly how to sub 6.8 into 6.9!
Would I be right in thinking we just calculate... (When ab = tt)
[tex]R_{tt} = R^c_{tct} = 0[/tex] where [tex]R^c_{tct}[/tex] is the Riemann curvature tensor.
Then we can use that,
[tex]\Gamma^c_{ab} = \frac{1}{2}g^{cd}(\partial_a g_{bd} + \partial_b g_{ad} - \partial_d g_{ab})[/tex]
to calculate [tex]R^c_{tct}[/tex] where we have...
[tex]g_{tt} = -e^{A(r)}[/tex]
[tex]g_{rr} = e^{B(r)}[/tex]
and so on...
Is this the right method? Seems like it's going to take a loooong while to do this though.
Last edited: